If you look at 3D games that allow you to control the camera using the mouse--most notably first-person and third-person shooter style games--you'll usually find two specific details:

By default, pushing the mouse forward makes the camera look up, and pulling back looks down.

The option to reverse this (forward=down) is called "invert Y axis" or something similar.

I've never understood that, and it's always seemed backwards to me, to the point where I get wildly disoriented in any game with default settings on. It seems intuitively obvious that the mouse (or, even more so, a thumbstick, which even looks kind of like a head sitting atop a neck) is modeling the perspective character's head. Move left, you look left. Move right, you look right. Push forward, the head pushes forward, and you look down... right?

In fact, this orientation was the default in a lot of early 3D games, such as flight simulators, MechWarrior 2, etc. But at some point it changed, and people started calling the intuitive orientation "inverted" and disabling it by default.

Are there any historical reasons behind this reversal of the default camera control orientation? Any articles, perhaps, on the rationale behind changing it, or studies showing why it was a desirable change to make?

Interestingly, I went from preferring "inverted" to the now-default mode while playing a game which required both first person mouse-look in 3D, as well as switching to a mouse pointer mode and clicking on items from the same perspective. For some reason, reconciling these two made me feel that the flight-sim mode really was inverted; and within a few months I switched over completely (this was after several years of competitive gaming, so not for a lack of prior experience).
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Daniel BFeb 26 '13 at 12:05

3 Answers
3

It seems intuitively obvious that the mouse (or, even more so, a
thumbstick, which even looks kind of like a head sitting atop a neck)
is modeling the perspective character's head.

Maybe this seems intuitively obvious to you, but not to everyone. To some it would seem intuitively obvious that moving the mouse "up" should move your view "up." I'm not suggesting either side is more correct--they both have their followers obviously--but they're certainly both within the realm of reasonable possible interpretations of what the mouse should do. Apparently you're in the minority, since your inclination received the "inverted" naming, but somebody had to.

After id Software's Doom, the game that popularized FPS games but
which did not support vertical aiming with a mouse (the y-axis served
for forward/backward movement), competitor 3D Realms' Duke Nukem 3D
became one of the first games that supported using the mouse to aim up
and down. This and other games using the Build engine had an option to
invert the Y-axis. The "invert" feature actually made the mouse behave
in a manner that users now regard as non-inverted (by default, moving
mouse forward resulted in looking down). Soon after, id Software
released Quake, which introduced the invert feature as users now know
it. Other games using the Quake engine have come on the market
following this standard, likely due to the overall popularity of
Quake.

If you stop calling it "pushing forward" on the joystick/mouse, and start calling it "pushing up" (which is the way that most players think of it -- particularly the ones who don't play flight simulators), then the "invert Y axis" name makes complete sense, since pushing up causes the player to look down.

Edit:

The fundamental issue here is people's mental models about what a game's controls do.

One group of people have this mental model: "if I press up, I should see more upward". That is, the controls are wired to the view, and what I do with the controls should have the same effect on the view.

Another group of people have this mental model: "If I press up, I'm swinging the camera upward, so I see more downward"; that is, the controls are wired to an object in the world, and the rendered view is merely a side-effect of the motion of these controlled objects in the world.

Neither viewpoint is 'right'. Lots of games have been made using each approach, and these days they mostly give you the option to switch it if you don't like the default. Mostly people have settled on "up means the view moves up" as "normal" and "up means the view moves down" as "inverted", but there have been plenty of games which named them in the reverse direction.

Incidentally, the same issue exists for left and right, for games which have a third-person camera. Some people think that pushing left means they should see more to the left, others think that pushing left means that the camera should swing to the left, and thus they should see more to the right. Some even feel differently about the two axes.

The important point is that options are presented to players, which lets everyone play according to their own preferred mental model, rather than obsessing over which approach is the correct one.

But they aren't pushing up. (Unless they're standing up and holding their mouse against a wall or something!) The mapping of forward to up makes sense on a 2D desktop, but not in 3D space.
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Mason WheelerFeb 26 '13 at 0:55

8

It seems like you're trying to have a debate which is operating on rational principles. This isn't a rational debate. People think of themselves as pushing "up" on the mouse because the mouse cursor moves up on their screen when they push the mouse forward. That's just the way it is, and that's why things are named the way they are.
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Trevor PowellFeb 26 '13 at 0:59

4

@MasonWheeler If it helps, think of it as steering the reticle rather than tilting the head.
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Cameron FredmanFeb 26 '13 at 1:00

1

Yup. And there's the same issue for left/right in 3D third-person games -- am I moving the reticle, or am I moving the camera. Many (most?) such games give an 'invert x axis' option there as well, because precisely the same issue exists; some people think that moving the mouse right should mean I should see more to the right (steering the reticle), others think I should see more to the left (steering the camera around the player). Same deal.
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Trevor PowellFeb 26 '13 at 1:02

1

The Konami Code starts out with "UP UP DOWN DOWN" not "FORWARD FORWARD BACK BACK" - not sure why the spatial logic would change between the d-pad and a thumb stick. I could be the crazy one though!
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SpartanDonutFeb 26 '13 at 5:08

Also interesting to note that for standard GUI usage moving the mouse forward will move the pointer up on-screen, although I don't know how related that may or may not be.

At the time, true 3D was something new and strange and the best control schemes were still being worked out, so it shouldn't be surprising that the default used was the reverse of what many, if not most, now consider normal.

Oops.. you found the quake reference before me. +1
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Cameron FredmanFeb 26 '13 at 1:08

In fairness it's the most obvious first place to look for "why is X the way it is" questions in FPS land so I can't really claim credit
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Darth SatanFeb 26 '13 at 1:25

The question also mentions flight simulators and thumbsticks, which often use inverted controls, to mimick the controls of a real plane. I think players who are used to simulators will find inverted controls easier.
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TonioElGringoFeb 26 '13 at 7:01